JPH0643815B2 - Control method of dual fuel engine in LNG carrier - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for controlling a dual fuel engine in an LNG ship, and more specifically to an LNG ship in which vaporized gas and fuel oil are mixed in an LNG tank. The control method of the dual fuel engine in the above.

[Prior Art] Generally, in an LNG ship, the LNG in the tank receives external heat and is vaporized to rise in the tank. Therefore, a so-called dual fuel engine that supplies gas vaporized in this tank to the main engine and mixes with fuel oil has been conventionally used.

By the way, in this conventional dual fuel engine, in order to obtain the number of revolutions of the engine according to the ship speed, a signal is given to the governor and adjusted, and fuel oil or vaporized gas is supplied by the signal from the governor. I was trying to adjust the amount. Therefore, since the amount of vaporized gas generated usually changes due to changes in the outside air temperature, it is necessary to generate extra vaporized gas or increase fuel oil in order to adjust the supply amount while maintaining the tank internal pressure. In this case, there is a problem that energy is wasted, and in the latter case, consumption of expensive fuel oil needs to be increased.

On the other hand, it may not be necessary to maintain a predetermined ship speed depending on the operation mode of the ship. That is, there may be no problem even if the engine speed slightly changes.

[Object of the Invention]

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is LN.
It aims to reduce the operating cost as well as to effectively use the vaporized gas in the G vessel.

[Outline of Invention]

The present invention for achieving the above object provides a dual fuel engine of an LNG ship configured to supply vaporized gas and fuel oil in an LNG tank, the fuel oil supply amount being kept constant, and the LNG tank being supplied. The internal pressure is detected, and almost the entire amount of the vaporized gas is supplied by this signal, and the rotation speed is changed according to the change of the vaporized gas amount.
It is intended to provide a control method of a dual fuel engine in an NG ship.

That is, the present invention is an improvement of a dual fuel engine that operates by LNG vaporized gas and ordinary fuel, and supplies the entire amount of the vaporized gas and a fixed amount of ordinary fuel to the engine.

Therefore, the fuel supplied to the engine fluctuates as much as the vaporized gas fluctuates, and the speed of the engine changes accordingly.
For example, it is effective for navigation at night.

When the amount of vaporized gas in the daytime LNG is large and it is necessary to control the ship speed within a predetermined range, the engine is operated while controlling the total amount of vaporized gas and the amount of fuel by this amount of vaporized gas. It is a thing.

The amount of LNG vaporized gas generated is conveniently measured using a pressure transmitter.

〔Example〕

An embodiment of a method for controlling a dual fuel engine in an LNG ship according to the present invention will be described below with reference to the drawings.

In the figure, reference numeral 1 is an LNG tank mounted on an LNG ship, the internal pressure of the LNG tank 1 is detected by a pressure transmitter 2, and the signal thereof is led to a control device 3. The control device 3 operates the pressure transmitter 2 in response to a command from a control device (not shown) and sends a signal to the governor 4 to disconnect the governor 4 from the normal engine rotation instruction signal and switch to control by a constant pressure signal in the LNG tank 1. The operation is performed.

Reference numeral 5 denotes a governor arm having one end connected to the governor 4 and the other end connected to the balance arm 6.
The operation of is transmitted to the balance arm 6. The balance arm 6 is connected to a gas rack 7 for adjusting the supply amount of vaporized gas and a fuel oil rack 8 for adjusting the supply amount of fuel oil. Reference numeral 9 is a gas positioner, and 10 is a fuel oil positioner.

In the above configuration, normally, in response to a command from the control device, the governor 4 issues an engine speed instruction signal according to the ship speed,
With this signal, the governor arm 5, the balance arm 6,
The gas rack 7 and the fuel oil rack 8 are operated to supply the vaporized gas and the fuel oil required for a predetermined rotation speed to the dual fuel engine.

When the control device gives a command to the control device 3 when the engine is controlled in the above-described state, for example, when the operation state such as night operation does not need to keep a predetermined ship speed, the control device gives a command to the control device 3. Reference numeral 3 activates the pressure transmitter 2 and switches the signal from the governor 4 from the engine speed instruction signal to the constant tank pressure signal.

That is, the governor arm 5, the balance arm 6 and the gas rack 7 are operated so as to supply almost all of the vaporized gas amount generated so that the pressure in the tank 1 is kept constant. At this time, the fuel oil rack 8 is set so as to supply a constant amount of fuel oil.

Of course, the present invention is not limited to the above embodiment,
It is obvious that various changes and additions can be made without departing from the spirit of the invention.

〔The invention's effect〕

As is clear from the above description, according to the method for controlling a dual fuel engine in an LNG ship according to the present invention, it is possible to measure the effective use of energy in order to supply almost all of the vaporized gas generated in the tank to the engine. it can.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of a method for controlling a dual fuel engine in an LNG ship according to the present invention. 1 ... LNG tank, 2 ... Pressure transmitter, 3
...... Control device, 4 ...... Governor, 5 ...... Governor arm, 6 ...... Balance arm, 7 ...... Gas rack, 8 ......
Fuel oil rack, 9 ... Gas positioner, 10 ... Fuel oil positioner.

Claims (1)

[Claims] 1. A dual fuel engine of an LNG carrier, which is adapted to supply vaporized gas and fuel oil in an LNG tank, keeps the supply amount of the fuel oil constant and detects the internal pressure of the LNG tank. A method of controlling a dual fuel engine in an LNG ship, wherein substantially the entire amount of the vaporized gas is supplied by a signal, and the number of revolutions is changed according to the change in the vaporized gas amount.